1. Field of the Invention
The present invention relates to a hand brake lever assembly for actuating a parking brake in automotive vehicles. The invention is particularly concerned with a safety mechanism of a hand brake lever assembly of the stick type which includes a rod-like plunger mounted on a vehicle body structure for axial slidable movement and for rotation about its axis. The rod-like plunger is connected at one end thereof to a cable or other linkage leading to a parking brake, and a handle is attached to the other end of the plunger. A locking mechanism is associated with the plunger to retain the plunger in a pulled-out position against a returning effort of the parking brake acting thereon when it has been pulled by the driver in the act of pulling the handle. The locking mechanism arranged to be released by rotation of the plunger.
2. Discussion of the Background
In Japanese utility model early publication No. 60-134065, there has been proposed a hand brake lever assembly of this kind which includes a rod-like plunger mounted on a vehicle body structure for axial slidable movement and for rotation about its axis. The rod-like plunger is connected at one end thereof to a cable or other linkage leading to a parking brake, and a sleeve member is coaxially secured to the other end of the plunger for rotation therewith. A handle having a shaft extending therefrom is inserted into the sleeve member for axial movement and rotation about its axis. The sleeve member has an annular end wall formed with an annular cam surface facing in the direction opposite to the handle pulling force acting on the plunger. The handle shaft has an enlarged portion formed with an annular cam surface complementary with the annular cam surface of the sleeve member and contained within the sleeve member of axial movement and rotation about its axis. The annular cam surfaces are pressed in contact with each other under load of a compression spring in the sleeve member to retain the handle in a predetermined angular position in relation to the plunger.
The brake lever assembly enables a rotatable connection of the handle with the plunger for unitary rotation only when the handle is pulled such that actuation of the parking brake is maintained even when the handle is turned by being inadvertently touched by the driver's hands or legs while the parking brake is being actuated. In the brake lever assembly, the unitary rotation of the plunger with the handle is effected by frictional engagement force between the cam surfaces to release the locking mechanism. For this reason, if the frictional engagement force between the cam surfaces is insufficient due to weak pulling force of the handle, the unitary rotation of the plunger with the handle will not be effected to disable release of the locking mechanism.